Lower the first chapter title to put in a fancy header, have all subsequent pages look normal

Question

I have several chapters in a book. I want a fancy header above the first chapter, so on this page the chapter number and title should be typeset a little lower than usual (below the header). All subsequent pages and chapter titles should be typeset normally.

\documentclass[11pt]{book}

\usepackage{lipsum}
\usepackage{fancyhdr}
\fancypagestyle{firstpage}{
  \fancyhf{}
  \fancyhead{
    \begin{minipage}{\textwidth}
      {\sffamily Some information\\More information\\Another note\\This is a rather lengthy header\\foo\\bar\\buz\\blah\\beep}
    \end{minipage}
  }
}

\begin{document}

\chapter{A first chapter}
\thispagestyle{firstpage}

This is the first chapter. This page should include a fancy header
with some information, and as such the chapter number and title should
appear a little lower than for other chapters.

\lipsum[1-12]

\chapter{A second chapter}

This is the second chapter. It should be formatted normally, i.e., the
chapter number and title should appear at the top of the page, since
there is no special header here

\lipsum[13-19]

\end{document}

There are two problems:

1. The first chapter is not typeset low enough. It overlaps with the header.
2. All subsequent pages are typeset much lower. The bottom margin is almost 0, and the top margin is huge.

LaTeX outputs a warning too:

Package Fancyhdr Warning: \headheight is too small (12.0pt): 
 Make it at least 133.13336pt.
 We now make it that large for the rest of the document.
 This may cause the page layout to be inconsistent, however.

This seems to be the problem, but I don't understand how to fix it. If I put

\setlength{\headheight}{134pt}

inside the \fancypagestyle{firstpage}{...} declaration, then the first chapter title is typeset lower, and all subsequent pages look fine. This is close to what I want. However, the bottom margin of the first page is still almost 0, and so the text at the end of the first page goes all the way to the bottom. How to fix this last problem?

This does not appear to be a duplicate. There are two related questions:

• fancyhdr - anomalous behaviour on first page

• Fancy header on the first page is not the same on subsequent pages

However, in those cases setting \headheight seems to solve it, and they do not appear to experience my latter problem.

Answer 1

The trick is to set the minipage to have zero height, so it won't influence the head height for the subsequent pages (at the eyes of fancyhdr). This requires that the rule is typeset in the minipage, rather than printing the usual head rule that would appear in the wrong position.

I also adjusted the space above chapter titles; the easiest way is with etoolbox: instead of 50pt (here 50\p@) I set 80pt, adjust to suit. The first patch to \chapter is meant to avoid the need for \thispagestyle{firstpage} in the document.

Setting the head height to 13.6pt is required by the fact you use 11pt size.

\documentclass[11pt]{book}

\usepackage{etoolbox}
\usepackage{fancyhdr}

\usepackage{lipsum} % just for the example

\setlength{\headheight}{13.6pt}
\fancypagestyle{firstpage}{%
  \renewcommand{\headrulewidth}{0pt}%
  \fancyhf{}%
  \fancyhead{%
    \begin{minipage}[t][0pt]{\textwidth}
    \sffamily
    Some information\\
    More information\\
    Another note\\
    This is a rather lengthy header\\
    foo\\
    bar\\
    buz\\
    blah\\
    beep\strut
    \hrule
    \end{minipage}% <--- don't forget
  }%
}

\patchcmd{\chapter}{plain}{firstpage}{}{} % avoid the need of \thispagestyle after \chapter
\makeatletter
\patchcmd{\@makechapterhead}{50\p@}{80\p@}{}{}  % chapter head is lower
\patchcmd{\@makeschapterhead}{50\p@}{80\p@}{}{} % starred chapter head is lower
\makeatother

\begin{document}

\chapter{A first chapter}

This is the first chapter. This page should include a fancy header
with some information, and as such the chapter number and title should
appear a little lower than for other chapters.

\lipsum[1-12]

\chapter{A second chapter}

This is the second chapter. It should be formatted normally, i.e., the
chapter number and title should appear at the top of the page, since
there is no special header here

\lipsum[13-19]

\end{document}